How hydrogen fuel cells work

The essence of fuel cell is the "inverse" device of hydroelectricity electrolysis, which is mainly composed of three parts: anode, cathode and electrolyte. The anode is hydrogen electrode and the cathode is oxygen electrode. In general, the anode and cathode contain a certain amount of catalyst, which is used to accelerate the electrochemical reaction occurring at the electrode. Between the poles are electrolytes.

Taking proton exchange membrane fuel cell (PEMFC) as an example, its working principle is as follows:

(1) Hydrogen reaches the anode through the pipe or air guide plate;

(2) Under the action of the anodic catalyst, one hydrogen molecule dissociates into two hydrogen protons and two electrons are released. The anodic reaction is as follows:

H2→2H++2e。

(3) At the other end of the battery, oxygen (or air) reaches the cathode through the pipe or the air guide plate. Under the action of the cathode catalyst, oxygen molecules and hydrogen ions react with the electrons reaching the cathode through the external circuit to form water. The cathode reaction is: 1/2O2+2H++ 2E →H2O

The total chemical reaction is H2+1/2O2 = H2O

Electrons form direct current in the external circuit. Thus, as long as hydrogen and oxygen are continuously supplied to the anode and cathode of the fuel cell, electrical energy can be continuously exported to the load of the external circuit.